There are two options for grilling halloumi — either in a grill basket or on foil: If you have a rectangular, flat-bottomed grill basket with a fine mesh then that will work, if you don’t, then I’d recommend grilling it on a piece of tin foil
Approximate quantities: 16-18 ounces of halloumi cheese, sliced into even rectangles; 2 tablespoons of olive oil; 1 tablespoon of finely chopped scapes, chives, or scallions greens
Slice the halloumi into rectangles, place in a large, rectangular Pyrex baking dish or on a sheet pan, drizzle oil and some sort of finely chopped allium, I’ve used garlic scape pesto in this photo, but chives or scallion greens will also will do
Grill either in a rectangular, flat-bottomed grill basket with a fine mesh on low-heat for 4-6 minutes, turning halfway through; allow to cool and then chop into squares
If you don’t have a rectangular, flat-bottomed grill basket with a fine mesh, lay the halloumi slices out on a sheet of foil and grill on low-heat for 4-6 minutes, turning halfway through; when they have browned, slide the entire sheet of tin foil off of the grill and on to a cutting board; allow to cool and then chop into squares
The variable here is your grill and it’s temperatures. I’ve provided a heat and time range for everything that should work for almost all grills.
Almost everything needs to be turned, or if it’s in a grill basket a good shake at the halfway point will work, so what I’d recommend is plan to check it and turn it halfway through the shorter time range that I suggest, and then, to check it again for doneness, at the end of the shorter time range. This way, if you grill doesn’t run as hot, and you can see that you need more time, it’s easy to leave the second side on for a few more minutes.